Rajon Rondo has a torn ACL. Widespread sentiment is that it’s time to abandon all hope and start the painful rebuilding project.

Not yet, Bostonians. …

Long-term, things couldn’t look much worse unless Michael Jordan bought the team. Short-term, however, there are still reasons to believe the Celtics will be all right.

By all right, I mean this was never going to end like Stripes, where Murray saved his Army platoon and returned home a hero. Rondo was never going to deliver an NBA title this season. But he and the Celtics were capable of getting into the playoffs and doing their usual Rasputin routine.

Ever since they won the 2008 NBA title, almost everybody expected them to completely calcify and disappear. Almost everybody has always been wrong.

After pushing Miami to seven playoff games last year, I realized it’d be stupid to count Boston out until Doc Rivers retires or Paul Pierce turns 60 or Kevin Garnett stops acting like Sgt. Hulka.

He’s still yammering like a drill sergeant, but the Celtics are only 21-23. They were hanging on to the final playoff spot with Rondo. So beyond blind faith, why shouldn’t Celtics fans be very depressed this morning?

Look to the Chicago Bulls. Derrick Rose has been out all season recovering from ACL surgery, yet the Bulls lead the Central Division and have almost as many wins as the Heat.

The Celtics can still muster all that. The offense will be slower and a lot less fun without Rondo going for a triple-double every night. But Rivers can re-tool it and squeeze some life out of Jason Terry, Avery Bradley and Courtney Lee.

Like Chicago, the playoffs are when they’ll really miss their All-Star point guard. Miami will run everybody out of the building. But that brings up another reason for hope.

The Celtics are in the Eastern Conference. A team with Pierce, Garnett and three guys from the Brockton YMCA could make the playoffs.

“We showed we’re capable,” Pierce said after Sunday’s double-overtime win over Miami. “We know with or without Rondo we still have the depth to compete with everybody.”

Well, almost everybody in the East. All those who feel now is the time to blow up this team need to remember that. For one thing, it’s not nearly as easy as it sounds with the mountain of salary-cap implications.

Garnett is in the first year of a three-year, $34 million deal. There’s not much of a market for a 36-year-old center lugging that contract around.

Pierce is more attractive, and Rudy Gay rumors have heated up. They make about the same ($16 million), and Pierce is guaranteed only $4 million next year.

That makes sense for Memphis. It doesn’t for Boston, since Gay is guaranteed $37 million the next two seasons. Besides, he’s Rudy Gay.

If the Celtics want to make another playoff run, they are better off with what they have. And that’s what the Master Plan always called for in Boston.

Boston long ago decided to ride its Big Three into the sunset. That was originally Pierce, Garnett and Ray Allen. Now it’s Pierce, Garnett and Rondo.

Actually, now it’s Pierce, Garnett and Bill Murray flashbacks. But once the shock wears off in Boston, there are plenty of reasons not to let depression completely set in.